Method and system for wireless local area network (wlan) long symbol duration migration

ABSTRACT

A method performed by a STA may comprise receiving data of a MU-HE-PPDU, from an AP. The MU-HE-PPDU may comprise a HE-SIG-A field, a first HE-SIG-B portion and a second HE-SIG-B portion. The first HE-SIG-B portion may be received on a first channel and the second HE-SIG-B portion may be received on a second channel which is different than the first channel. The first HE-SIG-B portion may include one or more STA identifiers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/284,891, filed on Feb. 25, 2019, which is a continuation of U.S.patent application Ser. No. 15/555,786 filed on Sep. 5, 2017, whichissued as U.S. Pat. No. 10,218,463 on Feb. 26, 2019, which is the U.S.National Stage, under 35 U.S.C. § 371, of International Application No.PCT/US2016/021240 filed Mar. 7, 2016, which claims the benefit of U.S.Provisional Application No. 62/129,613, filed Mar. 6, 2015, the contentsof which are hereby incorporated by reference herein.

BACKGROUND

A wireless local area network (WLAN) in Infrastructure Basic Service Set(BSS) mode has an Access Point (AP) for the BSS and one or more stations(STAs) associated with the AP. The AP typically has access or interfaceto a Distribution System (DS) or another type of wired/wireless networkthat carries traffic in and out of the BSS. Traffic to STAs thatoriginates from outside the BSS arrives through the AP and is deliveredto the STAs. Traffic originating from STAs to destinations outside theBSS is sent to the AP to be delivered to the respective destinations.Traffic between STAs within the BSS may also be sent through the APwhere the source STA sends traffic to the AP and the AP delivers thetraffic to the destination STA. Such traffic between STAs within a BSSis really peer-to-peer traffic. Such peer-to-peer traffic may also besent directly between the source and destination STAs with a direct linksetup (DLS) using an 802.11e DLS or an 802.11z tunneled DLS (TDLS). AWLAN in Independent BSS (IBSS) mode has no AP and STAs communicatedirectly with each other. This mode of communication is referred to as“ad-hoc” mode of communication.

In the current 802.11 infrastructure mode of operation, the AP transmitsa beacon on a fixed channel called the primary channel. This channel is20 megahertz (MHz) wide and is the operating channel of the BSS. Thischannel is also used by the STAs to establish a connection with the AP.

SUMMARY

A method and a system are disclosed for wireless local area network(WLAN) long symbol duration migration toward packets having larger FastFourier Transform (FFT) sizes for data transmission. The WLAN mayoperate in Infrastructure Basic Service Set (BSS) mode with an AccessPoint (AP) and onepg, or more stations (STAs). An AP may receive anassociation request from a STA. The AP may then create an associationidentifier (AID) for the STA. Further, the AP may determine a mediaaccess control (MAC) address or representation of a MAC address, whereinthe representation includes a Receive Address (RA) or Transmit Address(TA) or both. The representation may be a partial association identifier(PAID). The AP may determine the PAID according to the AID. The AP maycheck for PAID collisions.

The AP may then transmit the representation in an association responseframe based on a determination that there are no PAID collisions.Further, the AP may cycle through possible AIDs to find one for use inavoiding collisions based on a determination that there are PAIDcollisions. The AP may then transmit an association response based onthe AID for use in avoiding collisions. The AP may use a first set and asecond set of equations to create the PAID.

A STA may perform packet detection and decode a legacy preamble of adetected packet including a legacy short training field (L-STF), alegacy long training field (L-LTF), and a legacy signal (L-SIG) field.The STA may decode a high efficiency signal A (HE-SIG-A) field to obtaina first partial association identifier (PAID) comprising groupinformation. If the decoded group information matches group informationstored in a memory of the STA, the STA may decode a high efficiency (HE)preamble and a high efficiency signal B (HE-SIG-B) field of the detectedpacket. The HE-SIG-B field may include a station identifier within thegroup. When the group information is combined with the stationidentifier, the STA may determine an accurate address.

A method performed by an AP may comprise transmitting a multi-user (MU)HE physical layer convergence procedure (PLCP) protocol data unit (PPDU)(MU-HE-PPDU), on a first 20 megahertz (MHz) channel and a second 20 MHzchannel, to a plurality of stations (STAs). The MU-HE-PPDU may comprisea high efficiency signal A (HE-SIG-A) portion carried on the first 20MHz channel and the second 20 MHz channel. The MU-HE-PPDU may comprise afirst high efficiency signal B (HE-SIG-B) portion carried on the first20 MHz channel and a second HE-SIG-B portion carried on the second 20MHz channel.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is a diagram of an example of a Very High Throughput (VHT)physical (PHY) layer convergence procedure (PLCP) protocol data unit(PPDU) format defined in 802.11ac;

FIG. 3 is a diagram of an example of a Very High Throughput Signal A(VHT-SIG-A) field defined in 802.11ac;

FIG. 4 is a diagram of an example of a Very High Throughput Signal B(VHT-SIG-B) field defined in 802.11ac;

FIG. 5 is a diagram of another example of a VHT PPDU format;

FIG. 6 is a diagram of an example of a partial association identifier(PAID) as defined in 802.11ac;

FIG. 7 is a diagram of a PPDU format with a larger Fast FourierTransform (FFT) size for data transmission;

FIG. 8 is a diagram of an example of a SIG field of a short preamble in802.11ah;

FIG. 9 is a diagram of an example of a PAID for Non-Data Packet (NDP)frames in 802.11ah;

FIG. 10 is a diagram of an example of a PAID for non-NDP and non-1 MHzPPD frames in 802.11ah;

FIG. 11 is a diagram of an example of a media access control (MAC) frameformat defined in 802.11ac;

FIG. 12 is a diagram of an example of a PAID collision;

FIG. 13 is a diagram of exemplary frame designs;

FIG. 14 is a diagram of an example of an identifier (ID) in a PLCPheader;

FIG. 15 is a diagram of another example of an ID in a PLCP header;

FIG. 16 is a diagram of yet another example of an ID in a PLCP header;

FIG. 17 is a diagram of an example of a PAID discovery request frame;

FIG. 18 is a diagram of an example of a global PAID discovery requestframe;

FIG. 19 is a diagram of an example of a PAID discovery response frame;

FIG. 20 is a diagram of an example of a PAID change frame duringassociation response;

FIG. 21 is a diagram of an example of an association procedure with PAIDcollision aware AID assignment;

FIG. 22 is a diagram of an example of a PAID change frame;

FIG. 23A is a diagram of an example of sub-channels and basic channels;

FIG. 23B is another diagram of an example of sub-channels and basicchannels in which for different users, at the same instant in time,bandwidth allocations may be different;

FIG. 23C is a third example diagram of sub-channels and basic channelsin which multiple sub-channels may be allocated to a STA eithercontiguously or non-contiguously;

FIG. 24 is a diagram of an example of multi-resolution coding of aduration field on 4 sub-channels;

FIG. 25A is a diagram of an example SIG design for spectral unequalcoding for signal fields;

FIG. 25B is another example diagram of an example SIG design forspectral unequal coding for signal fields in which a HE-SIG-A field, maybe coded and modulated on a basic channel and repeated on the otheracquired channels;

FIG. 25C is a third example diagram of an example SIG design forspectral unequal coding for signal fields in which a basic channel maycontain one sub-channel; and

FIG. 26 is a diagram of an example of spectral unequal coding utilizedto encode SIG information on multiple sub-channels.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a Node-B, an eNode B,a Home Node B, a Home eNode B, a site controller, an access point (AP),a wireless router, and the like. While the base stations 114 a, 114 bare each depicted as a single element, it will be appreciated that thebase stations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple-output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1.times., CDMA2000 EV-DO, Interim Standard 2000 (IS-2000),Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), GlobalSystem for Mobile communications (GSM), Enhanced Data rates for GSMEvolution (EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 106.

The RAN 104 may include eNode-Bs 140 a, 140 b, 140 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 140 a, 140 b, 140c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 140 a, 140 b, 140 c may implement MIMO technology. Thus,the eNode-B 140 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 140 a, 140 b, 140 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1C, theeNode-Bs 140 a, 140 b, 140 c may communicate with one another over an X2interface.

The core network 106 shown in FIG. 1C may include a mobility managemententity gateway (MME) 142, a serving gateway 144, and a packet datanetwork (PDN) gateway 146. While each of the foregoing elements aredepicted as part of the core network 106, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MME 142 may be connected to each of the eNode-Bs 140 a, 140 b, 140 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 142 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the eNode Bs 140 a,140 b, 140 c in the RAN 104 via the S1 interface. The serving gateway144 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 144 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 144 may also be connected to the PDN gateway 146,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices. An access router (AR) 150 of a wireless local area network(WLAN) 155 may be in communication with the Internet 110. The AR 150 mayfacilitate communications between APs 160 a, 160 b, and 160 c. The APs160 a, 160 b, and 160 c may be in communication with stations (STAs) 170a, 170 b, and 170 c.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 108. In addition, the corenetwork 106 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

The fundamental channel access mechanism in an 802.11 system may beCarrier Sense Multiple Access with Collision Avoidance (CSMA/CA). Inthis mode of operation, every STA, including the AP, may sense theprimary channel. If the channel is detected to be busy, the STA may backoff. Hence only one STA can transmit at any given time in a given BasicService Set (BSS).

For reference, 802.11n, and 802.11ac, have been defined for operation infrequencies from 2 to 6 gigahertz (GHz). In 802.11n, High Throughput(HT) STAs can use a 40 megahertz (MHz) wide channel for communication.This may be achieved by combining a primary 20 MHz channel, with anotheradjacent 20 MHz channel to form a 40 MHz wide channel. In 802.11ac, VeryHigh Throughput (VHT) STAs can support 20 MHz, 40 MHz, 80 MHz and 160MHz wide channels. While 40 MHz and 80 MHz channels may be formed bycombining contiguous 20 MHz channels similar to 802.11n above, a 160 MHzchannel may be formed either by combining 8 contiguous 20 MHz channelsor two non-contiguous 80 MHz channels (80+80 configuration).

As an example for the “80+80” configuration, the data, after channelencoding, may be passed through a segment parser that divides it intotwo streams. Inverse Fast Fourier Transform (IFFT) and time domainprocessing may be done on each stream separately. The streams may thenbe mapped on to the two channels and the data may be sent out. On thereceiving end, this mechanism may be reversed and the combined data maybe sent to the media access control (MAC).

For reference 802.11af, and 802.11ah, have been introduced for operationin frequencies that are less than 1 GHz. For 802.11af, and 802.11ah, thechannel operating bandwidths may be reduced as compared to 802.11n, and802.11ac. 802.11af may support 5 MHz, 10 MHz and 20 MHz wide bands in TVWhite Space (TVWS) while 802.11ah may support 1 MHz, 2 MHz, 4 MHz, 8 MHzand 16 MHz in non-TVWS. Some STAs in 802.11ah are considered to besensors with limited capabilities and may only support 1 and 2 MHztransmission modes.

In the existing WLAN systems which utilize multiple channel widths suchas 802.11n, 802.11ac, 802.11af, and 802.11ah, there may be a primarychannel which usually has a bandwidth equal to the largest commonoperating bandwidth supported by all STAs in the BSS. The bandwidth ofthe primary channel may be, therefore, limited by the STA that supportsthe smallest bandwidth operating mode. In the example of 802.11ah, theprimary channel may be 1 or 2 MHz wide if there are STAs that may onlysupport 1 and 2 MHz modes, while the AP and other STAs in the BSS cansupport 4 MHz, 8 MHz and 16 MHz operating modes. All carrier sensing,and NAV settings, may depend on the status on the primary channel; i.e.,if the primary channel is busy, for example, due to a STA supportingonly 1 and 2 MHz operating modes transmitting to the AP, then the entireavailable frequency bands may be considered busy, even though majorityof it stays idle and available. In 802.11ah and 802.11af, all packetsmay be transmitted using a clock that is down clocked 4 or 10 times ascompared to the 802.11ac specification.

In the United States, the available frequency bands which can be used by802.11ah may be from 902 MHz to 928 MHz. In Korea it may be from 917.5MHz to 923.5 MHz; and in Japan, it may be from 916.5 MHz to 927.5 MHz.The total bandwidth available for 802.11ah may be 6 MHz to 26 MHz,depending on the country code.

To improve spectral efficiency, 802.11ac has introduced the concept fordownlink Multi-User MIMO (MU-MIMO) transmission to multiple STAs in thesame symbol's time frame, e.g. during a downlink OFDM symbol. Thepotential for the use of downlink MU-MIMO is also currently consideredfor 802.11ah. It is important to note that since downlink MU-MIMO, as itis used in 802.11ac, may use the same symbol timing to multiple STAs,interference of the waveform transmissions to multiple STAs may not bean issue. However, all STAs involved in MU-MIMO transmission with the APmay use the same channel or band, and this may limit the operatingbandwidth to the smallest channel bandwidth that is supported by theSTAs which are included in the MU-MIMO transmission with the AP.

IEEE 802.11ac may support communications using the entire availablebandwidth for a particular resource allocation. OFDMA technologies mayenable more efficient utilization of spectral resources and may becurrently supported by the WiMax and LTE communications protocols. IEEE802.11ax may enhance the performance of 802.11ac, including possiblyaddressing spectral efficiency, area throughput, and robustness tocollisions and interference.

In an example, 802.11ax systems may use a modified symbol duration andphysical (PHY) header format. The modified symbol duration may be alonger duration. The data symbols in a high efficiency (HE) PHY layerconvergence procedure (PLCP) protocol data unit (PPDU) may use adiscrete Fourier transform (DFT) period of 12.8 microseconds (us) andsubcarrier spacing of 78.125 kilohertz (kHz). Moreover, data symbols inan HE PPDU may support guard interval durations of 0.8 us, 1.6 us and3.2 us. An HE PPDU may include the legacy preamble (legacy shorttraining field (L-STF), legacy long training field (L-LTF) and legacysignal (L-SIG)), duplicated on each 20 MHz, for backward compatibilitywith legacy devices. A High Efficiency Signal A (HE-SIG-A) field, forexample using a DFT period of 3.2 us and subcarrier spacing of 312.5kHz, may be duplicated on each 20 MHz after the legacy preamble toindicate common control information.

Methods that have been developed to address these requirements for802.11ax are known as Coordinated Orthogonal Block-based ResourceAllocation (COBRA), and Multi-User Parallel Channel Access (MU-PCA).These technologies may enable transmissions over a smallerfrequency-time resource unit than is possible in 802.11ac. Thus multipleusers may be allocated to non-overlapping frequency-time resourceunit(s), which may enable simultaneous transmission and reception onorthogonal frequency-time resources. This may allow the frequency-timeresources to be more efficiently utilized, and the quality of service(QoS) may also be improved. A sub-channel may be defined as a basicfrequency resource unit that an AP may allocate to a STA. As an example,keeping the requirement of backward compatibility with 802.11n/ac inmind, a sub-channel may be defined as a 20 MHz channel.

FIG. 2 is a diagram of an example of a VHT PPDU format defined in802.11ac. A PHY header defined in 802.11 may normally include a legacyshort training field 204, legacy long training field 206, and a legacysignaling field 208. With a different version, the PHY header maycontain a legacy part 202 and a non-legacy part 210. Non-legacy part 210includes a VHT-SIG_A 212, a VHT-STF 214, a VHT-LTF 216, a VHT-SIG-B 218,and data 220 FIG. 3 is a diagram of an example of a VHT-SIG-A fielddefined in 802.11ac which may include two structures. In an example, aVHT-SIG-A1 may have a defined structure 320. VHT-SIG-A1 320 may includea bandwidth field 322, a reserved bit field 324, an STBC field 326, agroup ID field 328, an NSTS/partial AID field 330, a TXOP_PS_NOT_ALLOWEDfield 332, and a reserved bit field 334. In a further example, aVHT-SIG-A2 may also have a defined structure 340. VHT-SIG-A2 340 mayinclude a short guard interval (GI) field 342, a short GI NSYMdisambiguation 344, an SU/MU[0] coding field 346, an LDPC extra OFDMsymbol 348, a SU VHT-MCS/MU[1-3] coding field 350, a beamformed field352, a reserved bit 354, a CRC 356, and a tail 358.

FIG. 4 is a diagram of an example of a VHT-SIG-B field 400 defined in802.11ac. In an example, a VHT-SIG-B 400 may include several fieldswhich include a VHT-SIG-B length 402, a VHT-MCS 404, a reserved field406, a tail 408, and a field indicative of a total number of bits 410

FIG. 5 is a diagram of another example of a VHT PPDU format. FIG. 5includes a L-STF 502, a L-LTF 504, an L-SIG 506, a VHT-SIG_A 508, aVHT-STF 510, a VHT-LTF 512, a VHT-SIG-B 514, and data 516. In an examplein 802.11, the transmit MAC address (TA) and receive MAC address (RA)may be signaled in MAC header 528, which is modulated and coded togetherwith the data field 516. Data field may also include mac body 520 andframe check sequence (FCS)_522. MAC addresses may be universally unique.Further, in an example in 802.11ac, a partial association identifier(PAID) (compressed from association identifier (AID) and BSS identifier(ID) (BSSID)) may be included in the VHT-SIG-A field to indicate thereceiver ID for SU transmission. However, the PAID may not be unique.

FIG. 6 is a diagram of an example of a PAID as defined in 802.11ac. Inan example in 802.11ac, the PAID may be set based on the table in FIG. 6and be derived from the 48-bit BSSID and the 16-bit AID of the STA(s).In a further example, the PAID may include settings for the TXVECTORparameters GROUP_ID and PARTIAL_AID. On a condition a PPDU is addressedto an AP with group_ID set to 0, the PAID may be defined according tobits 39 to 47 of the BSSID. On a condition a PPDU is addressed to a meshSTA with a group ID set to 0, a PAID may be defined according to bits 39to 47 of the RA. On a condition the PPDU is sent by an AP and addressedto a STA associated with that AP or sent by a DLS or TDLS STA in adirect path to a DLS or TDLS peer STA with a group ID is set to 63, thePAID may be set based on bits 0 to 8 of the AID, bits 44 to 47 of theBSSID, and bits 40 to 43 of the BSSID.

FIG. 7 is a diagram of a PPDU format with a larger Fast FourierTransform (FFT) size for data transmission. In an example, 802.11ax mayconsider a larger FFT size for data transmission. With reference to FIG.7, the header portion of the PPDU has a 64 FFT size while the dataportion is of size 256 FFT. This is in contrast to legacy 802.11 systemsin which every OFDM symbol is modulated using 64 point IFFT.

FIG. 8 is a diagram of an example of a SIG field of a short preamble in802.11ah. In an example, a SIG field of a short preamble may includeseveral fields. Bit 0 may be reserved, bit 1 may be set to 1 if allspatial streams have an STBC coding and may be set to 0 if no spatialstream has an STBC coding. Bit 2 may be set to the value of the TXVECTORparameter UPLINK INDICATION. Bits 3 and 4 may be set together as adecimal 0 for 2 MHz, a 1 for 4 MHz, a 2 for 8 MHz, and a 3 for 16 MHz.Bits 5 and 6 may be set together as a decimal 0 for 1 space time stream,a 1 for 2 space time streams, a 2 for 3 space time streams, and a 3 for4 space time streams. Further, in an example in 802.11ah, bits B7 to B15may contain the 9 bit PAID that is used to identify the receiver, forexample, a STA, group of STAs, or an AP. The PAID may be a function ofthe BSSID of the AP in the case of an uplink transmission or acombination of the BSSID of the AP and the AID of the STA(s) in the caseof a downlink transmission. Bit 16 may be set to 0 if a short guardinterval is not used in the data field and set to 1 if a short guardinterval is used in the data field. Bits 17 and 18 may be set together,wherein bit 17 may be set to 0 for BCC and a 1 for LDPC. If bit 17 isset to 1, bit 18 may be set to 1 if the LDPC PPDU encoding process of anSU PPDU results in one or more an extra OFDM symbol. Otherwise bit 18may be set to 0. If bit 17 is set to 0, bit 18 may be reserved and setto 1. Bits 19 through 22 may be used for an MCS index. If bit 23 is setto 1, channel smoothing is recommended. If bit 23 is set to 0, channelsmoothing is not recommended.

FIG. 9 is a diagram of an example of how a PAID may be used for Non-DataPacket (NDP) frames in 802.11ah. In an example, the PAID may includesettings for the TXVECTOR parameters PARTIAL_AID for NDP frames. For aframe that is addressed to an AP, a PAID may be used based on bits 39 to47 of the BSSID. A frame sent by an AP and addressed to a STA associatedwith that AP or sent by a DLS or TDLS STA in a direct path to a DLS orTDLS peer STA, or to a group of STAs with a common multicast AID and acommon BSSID may be based on a PAID determined from bits 0 to 8 of theAID, bits 44 to 47 of the BSSID, and bits 40 to 43 of the BSSID.Otherwise the PAID may be set to 0.

FIG. 10 is a diagram of an example of a PAID for non-NDP and non-1 MHzPPDU frames in 802.11ah. In an example, the PAID may include settingsfor the TXVECTOR parameters PARTIAL_AID for non-NDP and non-1 MHz PPDUframes. The formula used may be different for NDP frames and non-NDPframes or 1 MHz PPDU frames as shown in FIGS. 9 and 10.

FIG. 11 is a diagram of an example of a media access control (MAC) frameformat defined in 802.11ac. In an example in current 802.11 standards,each frame is comprised of a MAC header 1102, a frame body 1122 and aFCS 1124 as shown in FIG. 11. The MAC header may contain several fields.The MAC header may contain a frame control field 1104, which may containinformation such as Type, SubType, fragment and the like. The MAC headermay also contain a duration/ID field 1106, which may contain theinformation (in the unit of microseconds) used for a NAV setting. InPS-Poll frames, the duration/ID field may be used to indicate the STA'sAID. Further, the MAC header may contain a 1-4 address fields 1108 11101112 and 1116, which may contain up to four MAC addresses depending onthe Type of the frame. Typically, address 1 may contain the receiveaddress (RA) and is present in all frames. Address 2 may contain the TAand is present in all frames except ACK and CTS. Address 3 may bepresent in data and management frames. Address 4 may be only present indata frames and only when both the To DS and From DS bits are set. TheMAC header may also contain a sequence control field 1114, which maycontain a 4-bit fragment number and a 12-bit sequence number. Further,the MAC header may contain a QoS control field 1118, which may identifythe traffic class (TC) or traffic stream (TS) and other QoS relatedinformation about the frame. This field may be present in QoS dataframe. The MAC header may also contain an HT control field 1120, whichmay contain HT or VHT control information.

In an example, early packet determination may be supported. With current802.11 MAC/PHY header designs, the PHY header may contain the basicinformation required by the PHY layer to detect and decode the packet.However, the transmitter and receiver of the packet may not be includedin the PHY header. The PHY header may be modulated separately with thelowest modulation and coding scheme (MCS).

The MAC header, which includes the MAC address of the transmitter andthe receiver, may be modulated and coded together with the MAC body,which means the receiver has to decode the entire packet in order toread the MAC header. Moreover, the MAC header and the MAC body may beencoded with the same MCS, which means the MAC header is not as reliableas the PHY header.

It may not be possible to determine the transmitter and receiver of thepacket until the receiver decodes the entire packet, which bringsseveral design defects to the system. Firstly, the system may not bepower efficient since all the receivers have to listen to the entirepacket. Secondly, the MAC header may be modulated and encoded withhigher MCS, which makes the transmission of the MAC header not reliableenough. Thus, the receiver which failed to decode the MAC frame may notknow the information carried in MAC header, including the identities ofthe transmitter and the receiver. This may be a main reason that theremay not be a negative acknowledgement/repeat requested (NACK/NAK)design, an acknowledgement of not receiving the packet, implemented in802.11 systems.

In an example, a longer symbol duration may be supported for the802.11ax data portion. There may be more room to fully utilize theentire spectrum and design a more efficient and reliable packet headers.

The PAID may be a 9 bit field found in the SIG field of the preamblethat identifies the receiving AP or non-AP STA and may enable earlydetermination of the receiver of the packet without the need fordecoding the MAC frame. It may be used in 802.11ac and 802.11ah and maybe derived from the BSS ID in the case of the AP and a combination ofthe BSSID and STA AID in the case of a STA. In a dense network, theremay be a problem in which the PAID calculated for different STAs may beidentical. This may make it difficult for a STA to be uniquelyidentified. Methods to ensure that the PAID are unique may be needed.

FIG. 12 is a diagram of an example of PAID collision. In an example, aPAID may be used for early determination of the receiver of the packetwithout the need for decoding the entire MAC frame. Further, an AID,which may be 16 bits, may be unique within one BSS but not unique in anOverlapping BSS (OBSS) scenario 1200. A PAID, which may be 9 bits, maybe compressed from an AID and BSSID, and may not be unique even within aBSS. PAID collisions may happen, especially in an OBSS scenario. Asshown in FIG. 12, the PAID1 1202 may be used for communication betweenAP1 1206 and STA1 1208 and PAID1 1202 may be used for communicationbetween STA2 1205 and AP2 1202.

In a further example, different bandwidths may be supported. Withcurrent 802.11 PHY header designs, all the signaling fields, includingL-SIG field, HT-SIG field, VHT-SIG-A/VHT-SIG-B fields, and S1GSIG/SIG-A/SIG-B fields, may be transmitted over the basic or smallestchannel bandwidth. If the STA is operating on a channel which is widerthan the basic or smallest channel bandwidth, the SIG field may berepeated on the rest of channels. For example, with 802.11ac, theVHT-SIG-A and VHT-SIG-B fields may be transmitted over the 20 MHzchannel, and repeated on the rest of channels if needed. Thus, thewideband channel may not be fully utilized by the PHY signalingprocedures and associated fields.

In an example, early packet determination may be supported. With IEEE802.11n and 802.11ac standards, the DFT period may be defined as 3.2 us,and subcarrier spacing may be 312.5 kHz. While in 802.11ax, thefollowing may apply. The data symbols in an HE PPDU may use a DFT periodof 12.8 us and a subcarrier spacing of 78.125 kHz. Further, the datasymbols in an HE PPDU may support guard interval durations of 0.8 us,1.6 us and 3.2 us. Also, an HE PPDU may include the legacy preambleincluding L-STF, L-LTF and L-SIG fields, duplicated on each 20 MHz, forbackward compatibility with legacy devices. In addition, an HE-SIG-Ausing a DFT period of 3.2 us and subcarrier spacing of 312.5 kHz may beduplicated on each 20 MHz channel, after the legacy preamble, toindicate common control information.

FIG. 13 is a diagram of exemplary frame designs. Exemplary frame designsmay include a PHY header, MAC header and MAC frames. In the followingembodiments, a solution is provided that may move the receive address(RA) to the preamble using either a MAC address or a representation ofthe MAC address, which may include the PAID. This representation may beused to communicate the RA, the TA or a combination of both RA and TA.Further, examples and solutions disclosed herein may be extended tocover other FFT sizes, such as a 128 or 512 FFT size.

In an example, an accurate address/ID may be obtained by combiningelements in both the SIG-A and SIG-B fields. The accurate address/ID maynot be a universally unique address such as MAC address. However, it maybe accurate enough that the collision probability of the addresseswithin a network is almost zero. In one embodiment, the PAID/Group IDmay be placed in the SIG-A field, while a newly defined ID may be placedin the SIG-B field. In this example, this field may be referred to asthe PAID2 field. By combining the PAID/Group ID and the PAID2 field, aunique MAC address may be obtained even for scenarios where there may bePAID collisions.

For a downlink transmission with one or more STA(s) as a receiver, torepresent the RA, or for an uplink transmission with one or more STA(s)as the transmitter, to represent the TA, the ID in the SIG-B or PAID2field may be one of the following. The ID may be a function of theun-used AID bits in the current PAID formula (PAID2=f(AID[8:15]) forexample, dec(AID[8-12])). Also, the ID may be a new function of theBSSID and the AID (PAID2=f(AID, BSSID)). Further, the ID may be aspecific value that is set when a PAID collision is discovered. In thiscase, each time a new PAID value is estimated, the PAID2 may be set. Inone example, it may be incremented by the AP and communicated to theSTA(s).

Further, the ID in the SIG-B or PAID2 field may be conditionallyassigned, for example, assigned only if a PAID collision occurs. In oneembodiment, bit 23 in SIG-A may be set to 1 if the sub_PAID field is inuse. In scenarios where there are no collisions, bit 23 may be set tozero.

For an uplink transmission with an AP as the receiver to represent theRA or a downlink transmission with the AP as the transmitter torepresent the TA, additional unused bits of the BSSID may be used. As anexample, in the four bit case: PAID2=f(BSSID(35:38)).

In another embodiment, a full MAC address of the AP may be derived fromthe combination of IDs in the SIG-A and SIG-B fields. For example PAID2may be: PAID2=(BSSID[1:38]).

FIG. 14 is a diagram of an example of an ID in a PLCP header. Forexample, a more accurate ID may include ID=function (PAID1 (SIG-A),PAID2 (SIG-B)).

An example procedure may be comprised of the following. A STA may startperforming packet detection and decode the legacy preamble, includingthe L-STF, L-LTF and L-SIG fields 1402. The STA may decode HE-SIG-Afield 1404 and obtain PAID/group ID information 1406. Further, the STAmay compare its PAID/group ID with the detected PAID/group ID. If theSTA has the same PAID or is within the group, the STA may be a potentialreceiver of the packet. Otherwise, the STA may not be the receiver ofthe packet. The STA may use the PAID1 to narrow the possible addresses,or group IDs, to a particular set, for example, set A. The STA maycontinue to decode the HE pre-amble 1408 and HE-SIG-B field 1410. TheSTA may obtain PAID2 1412. The STA may combine the PAID obtained fromHE-SIG-A field and the PAID2 obtained from HE-SIG-B field. The STA maythen accurately determine the address, or group ID, from the Set A.

In another example procedure, an accurate address/ID may be obtained byplacing the entire AID in the SIG-B field with no ID defined in SIG-A.As the SIG-B field may be sent using a 256 pt FFT OFDM or similartransform, the size of the ID field in the SIG-B field may be largeenough to limit the potential effect of collisions.

For representing a RA for a downlink transmission with one or moreSTA(s) as a receiver or to represent the TA of an uplink transmissionwith one or more STA(s) as a transmitter, more bits may be used from theSTA(s) AID. In one embodiment, a 17 bit PAID may be used, allowing theentire 16 bit AID of the STA to be used in the PAID calculation asopposed to only the first 8 bits of the AID as used in the currentcalculation.

To represent the RA in an uplink transmission with an AP as the receiveror to represent the TA in a downlink transmission with the AP as thetransmitter, more bits may also be used from the APs BSSID. In oneembodiment, a 17 bit PAID may be used, allowing more of the 48 bit BSSIDto be used in the PAID calculation with PAID=f(BSSID[30-47]).

FIG. 15 is a diagram of another example of an ID in a PLCP header.Another example procedure may be comprised of the following. A STA maystart performing packet detection and may decode the legacy preamble,including L-STF, L-LTF and L-SIG fields 1502. The STA may decode theHE-SIG-A field 1504. The STA may continue to decode the HE pre-amble1506 and HE-SIG-B field 1508. The STA may obtain PAID2 1510. Further,PAID2 1510 may contain accurate address information for the STA todetermine the transmitter and/or the receiver of the packet 1500.

FIG. 16 is a diagram of yet another example of an ID in a PLCP header.In an example procedure, an accurate address/ID may be created byplacing the entire AID in the SIG-A field alone with no ID defined inthe SIG-B field. In this case, to limit the effect of collisions one ofthe following approaches may be used. For example, the number of bitsallocated to the PAID field may be increased. The PAID field may containan accurate address for identification of a transmitter and/or receiverof the packet 1600.

Also, multiple sets of equations may be created to be used to set thePAID field. Each set of PAID equations may be created to limit overlapwith the other sets. To create multiple sets of equations, a differentset of bits may be used within the BSSID and/or AID to create the PAIDfield. Also, same set of equations may be used to create the PAID fieldbut modulate the resulting PAID field using orthogonal orsemi-orthogonal codes. To ensure that the equation used is known at thetransmitter, a bit or set of bits may be set indicating the specificequation set used. This may be set in SIG-A for example using thereserved bit. Alternatively, in a hybrid approach with a combined PAIDin HE-SIG-A and HE-SIG-B fields, the specific equation set used may becommunicated in SIG-B. In an example, the use of the alternateequation(s) may be triggered only if a collision is detected.

An example procedure may be comprised of the following. A STA mayperform start of packet detection and decode the legacy preamble,including L-STF, L-LTF and L-SIG field. Further, the STA may decode theHE-SIG-A field and obtain PAID1. Also, the STA may then accuratelydetermine the address, or group ID, according PAID1.

In a further example for 802.11ac using downlink MU-MIMO, the group IDmay be included in the SIG-A field, and PAID may not be used. In thisprocedure, the group ID may be included in the HE-SIG-A field, and aversion of AID may be present in the HE-SIG-B field.

Using downlink MU transmission, the group ID and/or BSS color field maybe included in the HE-SIG-A field. In an alternative method, the groupID may be omitted. Further, with DL OFDMA transmission, the HE-SIG-Bfield may be separately coded and modulated on the sub-channel allocatedto each STA/user. The HE-SIG-B field carried by one sub-channel maycontain an AID. The STA with the corresponding AID may be allocated tothat sub-channel.

Using uplink MU transmission, the group ID and/or BSS color field may beincluded in the HE-SIG-A field. The same or common HE-SIG-A field may betransmitted by all the uplink simultaneous STAs. In an alternativemethod, instead of BSS color, the full BSSID or a partial BSSID may beincluded in the HE-SIG-A field. Further, using UL OFDMA transmissions,an alternative method and procedure may be applied. Each uplink STA mayform the HE-SIG-A field on the entire channel, but only transmit thesignals on assigned sub-channel(s), and transmit nothing on theunassigned sub-channels.

Using uplink OFDMA transmission, each STA may send a HE-SIG-B field onits assigned sub-channel(s). The STA may include its AID in the HE-SIG-Bfield on assigned sub-channel(s). Each STA may have its own HE-SIG-Bfield.

Further, using uplink MU-MIMO transmission, each STA may send a HE-SIG-Bfield on the entire bandwidth. The STA may include the AID in theHE-SIG-B field. Each STA may have a common HE-SIG-B field.

In a further example, a procedure for receiving and processing uplink MUtransmissions at a STA may be comprised of the following. A STA mayperform the start of packet detection and decode the legacy preamble,including the L-STF, L-LTF and L-SIG fields. Further, the STA may decodean HE-SIG-A field and obtain a direction bit, BSS color and/or group ID.The STA may determine the packet is for uplink multi-user transmission.A non-AP STA may determine the uplink transmission, and it may not bethe receiver of the packet. Further, an AP STA may compare its BSS colorwith the detected BSS color and determine whether it is a potentialreceiver. In another example, if a part of or the full BSSID isincluded, an AP STA may more accurately determine whether it a potentialreceiver. Also, the STA may continue to decode the HE preamble andHE-SIG-B field on all the sub-channels. The STA may obtain multipleAIDs. An AP STA, which may be the potential receiver of thetransmission, may compare the received AIDs with the group ID. If allthe AIDs corresponding to the users are identified by the group ID, theAP may then accurately determine it may be the receiver of thetransmission. In an example, the determination may be based on all theinformation obtained from BSS color/partial BSSID, group ID, and AIDs.

In a further example, a procedure for receiving and processing DL OFDMAtransmissions at a STA may be comprised of the following. A STA mayperform the start of packet detection and decode the legacy preamble,including the L-STF, L-LTF and L-SIG fields. Further, the STA may decodethe HE-SIG-A field and obtain the BSS color and group ID. The STA maydetermine that the packet is for DL OFDMA transmission. Also, the STAmay compare its BSS color and group ID with the detected BSS color andgroup ID. If the STA has the same BSS color and is part of the group,the STA may be a potential receiver of the packet. Otherwise, the STAmay not be the receiver of the packet. The STA may use the BSS color andgroup ID to narrow the possible number of addresses of the receiver orreceiver group, to a particular set, for example, Set A. In addition,the STA may continue decode the HE preamble and HE-SIG-B field on allthe sub-channels. The STA may obtain multiple AIDs. Further, the STA maycompare its AID with the obtained AIDs. If the STA's AID is carried oncertain sub-channel(s), the STA may be a receiver of the OFDMAtransmission and sub-channels assigned to the STA may be thesub-channels which carries the AID. The STA may then accuratelydetermine the address, or group ID, from a particular set, for example,the Set A.

In a further example, in 802.11ac and related specifications, the MACaddress of the transmitter (TA) and receiver (RA) may be carried in theMAC header. The MAC address may be a unique ID for a STA, which contains6 octets. With the longer symbol duration discussed in 802.11ax, theSIG-B field, which may be one OFDM symbol, may be able to carry one ormore MAC addresses.

In one example method, the RA may be included in the SIG-B field. Inanother example method, both the RA and TA may be included in the SIG-Bfield. In a third example method, a compressed version of RA and TA maybe included in the SIG-B field. The compressed version of RA and TA maybe a function of both RA and TA. For example, a bitwise operation, suchas OR, XOR, AND, may be used to combine RA and TA. Further, a modulooperation may be applied to the function.

In a fourth example method, the RA and TA may or may not be presented inSIG-B field depending on the parameter settings in SIG-A field, or therest of SIG-B field, or a combination of SIG-A and SIG-B fields. Forexample, for a responding frame, which may be transmitted following aprevious transmission without contention, RA may be present. As afurther example, for an initiating frame, which may be transmitted by aSTA which contended and acquired the channel, both the RA and TA may bepresent. As another example, to differentiate a responding frame and aninitiating frame, one bit may be utilized explicitly in one of signalingfield in the PLCP header. This bit may be referred to as the respondingbit or other terminology. Alternatively or in combination, an implicitsignaling method may be applied.

In an example, since one or more MAC addresses may be moved to the PLCPheader and the MAC header may be modified accordingly. The RA field maynot be present in the MAC header, and the TA field may be optionallypresent in the MAC header.

An example procedure for the fourth method, above, may be comprised ofthe following. A STA may perform start of packet detection and decodethe legacy preamble, including the L-STF, L-LTF and L-SIG fields.Further, the STA may decode HE-SIG-A field and obtain the respondingbit.

For a responding frame, the STA may determine whether it is part of thetransmission by checking whether it sent the previous frame to which theresponding frame responded. Also, the STA may continue decoding the HEpreamble and HE-SIG-B field. The STA may also obtain the RA field. Bychecking the RA field, the STA may determine whether it is the receiverof the transmission. If it is the receiver, by checking the previousframe the responding frame responded, the STA may determine thetransmitter of the current frame.

For an initiating frame, the STA may continue decoding the HE preambleand HE-SIG-B. According to the RA and TA field in HE-SIG, the STA mayuniquely determine the transmitter and receiver of the frame.

In a further example, the AP/STAs may use signaling and a procedure forPAID discovery. In this embodiment, a procedure may be defined to enablethe Partial AID of a STA, AP or set of STAs to be discovered by thenetwork. AP/STAs may use this procedure to make sure that the PAIDvalues associated with a specific node are accurate. This may benecessary in scenarios where PAID collision may occur such as a densenetwork with OBSSs where the density of APs and STAs may result in thesame PAID being assigned to multiple STAs.

In an example, a PAID discovery procedure may be initiated for aspecific PAID as follows. A PAID discovery request frame may be sent toenable an AP or STA find out the MAC address associated with a specificPAID. Further, all STAs that are identified with the sent out with thePAID may reply with a PAID response frame that includes the PAIDrequested for and an associated MAC address. In an example, the PAIDresponse frame may be aggregated with other MAC frames. In anotherembodiment, a global PAID request frame may request that all STAsassociated with a BSS reply with their PAID and corresponding MACaddress. In the event that there are multiple STAs that reply to thePAID request, a PAID collision mitigation procedure may be initiated.

In a further example, the PAID request frame may be transmitted from anAP to STA or vice versa. Further, the PAID request frame may bebroadcast from an AP to request that all STAs send their information into be checked for duplicates. Also, the PAID request frame may be arequest to a specific PAID so that all STAs with colliding PAIDs sendtheir information in.

FIG. 17 is a diagram of an example of a PAID discovery request frame1700. The exemplary PAID discovery request frame 1700 is comprised of aframe control field 1702, a duration field 1704, an RA field 1706, and aTA field 1708.

FIG. 18 is a diagram of an example of a global PAID discovery requestframe 1800. The exemplary global PAID discovery request frame 1800 isshown comprised of a frame control field 1802, a duration field 1804,and a TA field 1806.

FIG. 19 is a diagram of an example of a PAID discovery response frame1900. The exemplary PAID discovery response frame 1900 is showncomprised of a frame control field 1902, a duration field 1904, an RAfield 1906, a TA field 1908, and a current PAID field 1910.

In a further example, an AP/STA may use a procedure to assign a new PAIDtriggered by collision detection. In dense network scenarios, there maybe multiple STAs identified using the same PAID. In single BSSscenarios, this condition may be identified by the AP. In this case, theAP may decide to assign a new AID to the STA or may decide to change thePAID address using a different PAID address methodology as discussedabove. This may occur during the STA association process.

FIG. 20 is a diagram of an example of a PAID change frame 2000 which maybe used during an association response. The PAID change frame maysupport early packet detection and be used in association procedures.Exemplary PAID change frame 2000 is shown comprised of a frame controlfield 2002, a duration field 2004, an RA/target address 2006, a TA field2008, a PAID equation index field 2010, and a new PAID field 2012.

FIG. 21 is a diagram of an example of an association procedure with PAIDcollision aware AID assignment. The following example associationprocedure may be used. When a STA decides which AP it would like to beassociated with, the STA may send an association request to the AP. TheAP may receive the association request 2102 and create an AID for theSTA 2104. In an example, the AP may also calculate the PAID according tothe AID 2106. The AP may check the PAID estimated based on the AID toensure that there are no PAID collisions 2108. If there are no PAIDcollisions, the AP may send an Association Response frame to the STA. Inan example, the AP may assign the AID to the STA 2110. If there are PAIDcollisions, the AP may cycle through all possible Association IDs tofind one which avoids collisions 2112 and then send an AssociationResponse to the STA. If the AP is unable to find a non-colliding AID,the AP may not associate with the STA 2114. Also, the AP may use adifferent set of equations to create the PAID field, as discussed above.The AP may then send an Association Response to the STA. The AP may alsosend a PAID change frame or similar frame to indicate the use of adifferent PAID estimation equation. For example, the AP may use the PAIDequation index field 2010 of FIG. 20 and/or alternatively, a specificPAID address as shown in the new or modified PAID field 2012 of FIG. 20.

FIG. 22 is a diagram of an example of a PAID change frame 2200. Inscenarios in which multiple BSS are within range and are overlapping,this overlapping condition may be identified by the procedure disclosedabove. PAID change frame 2200 includes, for example, a frame controlfield 2202, a duration field 2204, a RA/target address field 2206, a TAfield 2208, a current PAID field 2210, and a new PAID field 2212. Thelength of a STAID or PAID may vary. In 802.11ax the STAID was changedfrom 8 bits to 11 bits. Current PAID field 2210 or new PAID field 2212may carry a STAID.

On discovery of a PAID collision, an AP may mitigate the effect ofcollisions by implementing the following example procedure. The AP maydetect the PAID problem above and may estimate a new PAID to send.Further, the AP may send the suggested PAIDs to STA with a MAC framecontaining the old PAID, the new PAID and MAC address of STA that achange is desired for. An example of a PAID change frame which may beutilized is shown in FIG. 22.

Further, the STA may send back an ACK to indicate that the change hasoccurred. The ACK may include the new PAID value or its correspondingMAC address or both.

In order to support early detection, it may be possible to move someinformation which may otherwise be carried in the MAC header to the SIGfield, for example, the HE-SIG-B field. The information mentioned abovemay include MAC addresses, the duration field and the like. The durationfield may be used for unintended STAs, to set NAV accordingly.

Support for multi-bandwidth transmission may be provided. In an example,modified methods and procedures to encode and transmit signal fields aredisclosed. As used herein, a sub-channel may refer to the smallestfrequency resource a STA may be allocated. A minimum sub-channelbandwidth may not be specified in 802.11ac or related specifications. Aminimum sub-channel bandwidth may be restricted to a set of allowedbandwidths, for example, 1, 2, 5, 10 and/or 20 MHz and the like.

A basic channel may refer to a smallest frequency resource that may beassigned to an individual STA. In the 802.11ac specification this maynot be less than 20 MHz. In this embodiment the smallest allowedfrequency resource may be smaller and/or larger than this. Usually, thebasic channel is the smallest channel which may be used to transmit afull version of the L-STF/L-LTF/L-SIG and SIG-A fields. As noted for802.11ac, the basic channel may refer to a 20 MHz bandwidth (BW)channel.

A sub-channel may have the same size as the basic channel. Or asub-channel may have a narrower BW than the basic channel. In the secondscenario, an OFDMA transmission may be possible on a basic channel.

Next generation HE WLAN systems may support multiple user transmissions,such as OFDMA, for both downlink and uplink. An extension to theexisting 802.11 systems may be to utilize the basic or smallest possiblechannel bandwidth as the preferred OFDMA sub-channel bandwidth. Forexample, the OFDMA sub-channel bandwidth on 2.4 GHz/5 GHz bands may be20 MHz or even smaller.

FIG. 23 is a diagram of examples of allocations of sub-channels andbasic channels. As shown in FIG. 23A, the bandwidth of a sub-channelallocated to a user may have a different bandwidth at different times.It should be noted that with reference to FIG. 23, bandwidth isexpressed in terms of frequency in the y axis and time is expressed bythe x axis. For example, user 1 data 2302 is roughly twice the size ofuser 1 data 2304 at a different time instance. The same is true for user2 data 2306 and user 2 data 2308.

FIG. 23B illustrates that for different users, at the same instant intime, the bandwidths allocated may be different. User 1 data 2310 isshown in a narrower sub-channel than user 2 data 2312 and user 2 data2312 is shown in a narrower sub-channel than user 3 data 2314.

FIG. 23C shows an example of how multiple sub-channels may also beallocated to a STA either contiguously or non-contiguously. Sub-channelsfor user 1 data 2316 and user 1 data 2320 are shown interspersed withsub-channels for user 2 data 2318 and user 2 data 2322. Since OFDMA liketransmissions may not be defined, the MAC/PHY procedures, and associatedsignaling for sub-channels, for example, smaller than 20 MHz, may not besupported.

In an example, STA1 may acquire the channel, and transmit a packet toSTA2 on one or more sub-channels. The transmission may represent asingle user transmission where STA1 may transmit a packet to STA2 usingpossible acquired sub-channels. Further, the transmission may be part ofa MU transmission. In a DL MU transmission scenario, STA1 may representan AP and STA2 may represent a non AP STA. STA1 may acquire multiplesub-channels, and transmit to multiple users, including STA2simultaneously. STA1 may assign one or more sub-channels to STA2.

In an uplink MU transmission scenario, STA1 may represent a non AP STA,and STA2 may represent an AP. STA1, together with other non AP STAs maytransmit to STA2 using uplink MU transmission. STA1 may use one ormultiple sub-channels.

In an example, spectral unequal coding may be utilized to encodesignaling information across multiple sub-channels, for example, theHE-SIG-B field. Each sub-channel may have a variable granularity thatrepresents the entire information field, wherein the granularity mayenable a low overhead.

FIG. 24 is a diagram of an example of multi-resolution coding of aduration field 2410 on 4 sub-channels 2402-2408. In an example, aduration field 2410 may be included in the HE-SIG-B field 2412. TheHE-SIG-B field 2412 may be carried on M sub-channels 2402-2408. In thisexample, the communication between a pair of STAs, for example, STA1 andSTA2, may be allocated to M sub-channels. The duration field may need touse N bits to be represented. The duration field may be divided into Mpieces and the first M-1 pieces may contain ceiling(N/M) bits each. Andthe last pieces may contain N-ceiling(N/M)*(M-1) bits. The HE-SIG-Bfield of the first sub-channel may carry the first piece, i.e.ceiling(N/M) most significant bit (MSB) of the duration field 2410. TheHE-SIG-B field of the second sub-channel may carry the second piece andso on, as shown in FIG. 24.

FIG. 25 is a diagram of example SIG designs for spectral unequal codingfor signal fields. In FIG. 25A, a common signal field, HE-SIG-A field2502, may be coded and modulated on a channel. This channel may befurther divided to multiple sub-channels, which may be assigned to oneor multiple users. In this example, the channel may be divided into foursub-channels 2504-2510 and assigned to one user. The second signalfield, e.g., HE-SIG-B field 2512, may be coded and modulated on theassigned sub-channels using spectral unequal coding procedures.

FIG. 25B, shows another example. A common signal field, for example, theHE-SIG-A field 2522, may be coded and modulated on a basic channel, andrepeated on the other acquired channels. Some of the sub-channels may beassigned to one user. In this example, a basic channel may contain 2sub-channels, for example sub-channel 1 2524 and sub-channel 2 2526 orsub-channel 3 2528 and sub-channel 4 2530. The 4 sub-channels may beassigned to a STA. The second signal field, for example, the HE-SIG-Bfield 2532, may be coded and modulated on the assigned sub-channelsusing spectral unequal coding procedures.

FIG. 25C shows a third example. In this example a basic channel maycontain one sub-channel. A common signal field, for example, HE-SIG-Afield 2542, may be coded and modulated on a basic channel. Foursub-channels 2544-2550 may be assigned to a STA. The second signalfield, for example, HE-SIG-B field 2552, may be coded and modulated onthe assigned sub-channels using spectral unequal coding procedures.

In an embodiment, a STA referred to as STA1, as a transmitter, mayfollow an example procedure. STA1 may determine the number ofsub-channels assigned or available for STA2, and denote the number as M.Further, STA1 may include M in one of its common signal fields. Forexample, it may include M in the HE-SIG-A field. M may be signaled asthe number of sub-channels directly, or using bandwidth field and/orother fields. Also, STA1 may begin spectral unequal coding on a secondsignal field, for example HE-SIG-B field, which may introduce differentHE-SIG-B fields from one sub-channel to another. As used herein, theSIG-B field on sub-channel k may be referred to as level k information.There may be increasingly fine granularity from level 1 to level M. Thesecond signal field may contain information such as duration, packetlength, STA IDs and the like. Level 1 information may be transmitted onthe first sub-channel and considered as the base information, or theinformation with the coarsest granularity. Level 2 information may betransmitted on the second sub-channel and considered as an extension tolevel 1 information, or the information with the finer granularity.Level M information may be contained on the Mth sub-channel. This maycontain the last resolution signal information or the finestinformation. In an example, the mapping between sub-channels and thegranularity levels may depend on the channel qualities of sub-channelsfor high reliability.

In an embodiment, a STA referred to as STA2, as an intended receiver,may follow an example procedure. STA2 may determine the number ofsub-channels assigned or available (M) by checking the common signalfield. For example, it may check the HE-SIG-A field. M may be signaledas the number of sub-channels directly, or using bandwidth field, and/orother fields.

Further, STA2 may begin spectral unequal decoding on a second signalfield, for example the HE-SIG-B field. The decoding procedure may beperformed on sub-channels in order. The first level may be obtained onthe first sub-channel. STA2 may obtain coarse information by detectingand decoding the first level signal alone. The second level signalinformation may be obtained on the second sub-channel. The secondresolution signal information may be considered as an extension to thefirst level information, or the information with the finer granularity,where a receiver may combine the first and second level information toobtain a finer or more accurate information than the first levelinformation. The Mth level signal information may be obtained on the Mthsub-channel. This may contain the last level signal information or thefinest information. By combining all the information from the M levels,the receiver may obtain the full information.

Unintended STAs may follow an example procedure. An unintended STA maydetermine the number of sub-channels assigned or available, M, bychecking the common signal field. For example, it may check the HE-SIG-Afield. M may be signaled as the number of sub-channels directly, orusing bandwidth field, and/or other fields. Depending on the capabilityof the unintended STA, it may perform decoding of the second signalfield on some sub-channels. The STA may decode the signal information onthe first sub-channel. If the information contained in this SIG field isenough for the receiver to determine if the packet is not for thereceiver, through unintended receiver detection, or the NAV setting forthe receiver, then the receiver may stop decoding procedure and set NAVaccordingly. Otherwise it may continue decoding procedure on the secondsub-channel. The STA may continue the similar decoding procedure untilit obtains enough information.

As used herein, one of ordinary skill in the art will appreciate andunderstand that a STA referred to herein may also be a STA utilized as arelay.

FIG. 26 is a diagram of an example of spectral unequal coding. In anexample, self-contained spectral unequal coding may be utilized toencode SIG information on multiple sub-channels, for example, theHE-SIG-B field 2602. Each sub-channel 2604-2610 may have aself-contained version of the entire information field 2612 which may beused to facilitate the recovery all of the signal information elements.

For example, an information field 2612 may be included in the HE-SIG-Bfield 2602. The information field may contain a duration field, STA IDs,packet length, and the like. The HE-SIG-B field may be carried on Msub-channels 2604-2610. In this example, the communication between STA1and STA2 may be allocated to M sub-channels. The information field maybe encoded by M different encoders 2614-2620. The encoders may or maynot be the same. The coding rates of each one of the encoders may or maynot be the same. The coding rates of the encoders may be different fromthe coding rate used for other signal fields, such as HE-SIG-A.

In another example method, the information field may be modulated andcoded with different MCSs on different sub-channels. The transmitter,STA1, may assign MCSs for the sub-channels. The MCS assignment mayconsider the sub-channel conditions. The MCSs for HE-SIG-B field may besignaled in HE-SIG-A field.

STA1, as a transmitter, may follow an example procedure. STA1 maydetermine the number of sub-channels assigned or available for STA2, anddenoted it as M. Further, STA1 may include M in one of its common signalfields. For example, it may include M in the HE-SIG-A field. M may besignaled as the number of sub-channels directly, or using the bandwidthfield and/or other fields. Also, the STA1 may select M encoders or M MCSlevers for SIG-B field on M sub-channels. The STA1 may signal theencoder and/or MCS information in the HE-SIG-A field. In addition, STA1may begin self-contained spectral unequal coding on a second signalfield, for example the HE-SIG-B field, which may introduce differentHE-SIG-B fields from one sub-channel to another. As used herein, theSIG-B field on sub-channel k may be referred to as level k information.Each level may contain self-contained information. The second signalfield may contain information such as duration, packet length, STA IDsand the like. Level 1 information may be encoded using encoder 1 or MCS1 and transmitted on the first sub-channel. Level 2 information may beencoded using encoder 2 or MCS 2 and transmitted on the firstsub-channel. Level M information may be encoded using encoder M or MCS Mand transmitted on the first sub-channel.

STA2, as a receiver, may follow an example procedure. STA2 may determinethe number of sub-channels M by checking the common signal field. Forexample, it may check the HE-SIG-A field. M may be signaled as thenumber of sub-channels directly, or using bandwidth field and/or otherfield. Further, STA2 may determine the coding schemes or MCS levels foreach sub-channel by checking the common signal field, for example, theHE-SIG-A field. Also, STA2 may begin self-contained spectral unequaldecoding on a second signal field, for example the HE-SIG-B field. Thedecoding procedure may be performed on each or some of the sub-channels.STA2 may perform a decoding procedure on one of the sub-channels. If theSIG-B field is decoded successfully, STA2 may stop the decodingprocedure. Otherwise, it may continue decoding one of the restsub-channels. STA2 may combine all of the received symbols, includingthem from the previously decoded sub-channel(s), together to decode theSIG-B field.

In another example, SIG procedures for a more efficient coding schememay be used. With current 802.11 standards, all the signaling fields maybe coded and modulated with the lowest MCS level, for example, MCS 0. Inan embodiment, higher MCS may be used for the HE-SIG-B field. In anexample, the MCS selection for the HE-SIG-B field may be implementationspecific. In an embodiment, the MCS set for the HE-SIG-B may be all ofthe MCSs defined in the system. Or in another embodiment, it may be asubset of the entire MSC set. For example, it may be a basic MCS set forwhich all the STAs in the BSS support. The MCS for the HE-SIG-B may besignaled in the HE-SIG-A field.

Although the examples described herein consider 802.11 specificprotocols, one of ordinary skill in the art will appreciate andunderstand that the examples are not restricted to this scenario and areapplicable to other wireless systems and RATs as well. Further, althoughthe term SIFS may be used herein to indicate various inter frame spacingin the examples of the designs and procedures, all other inter framespacing, such as RIFS or other agreed time interval, may be applied inthe same solutions.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A method performed by a station (STA), the methodcomprising: receiving data of a multi user (MU) high efficiency (HE)physical layer convergence procedure (PLCP) protocol data unit (PPDU)(MU-HE-PPDU), from an access point (AP), wherein the MU-HE-PPDUcomprises a high efficiency signal A (HE-SIG-A) field, the MU-HE-PPDUcomprises a first high efficiency signal B (HE-SIG-B) portion and theMU-HE-PPDU comprises a second HE-SIG-B portion, wherein the firstHE-SIG-B portion is received on a first channel and the second HE-SIG-Bportion is received on a second channel which is different than thefirst channel; wherein the first HE-SIG-B portion includes one or moreSTA identifiers.
 2. The method of claim 1, wherein the first HE-SIG-Bportion comprises a plurality of STA identifiers.
 3. The method of claim1, wherein the second HE-SIG-B portion comprises a STA identifier whichis different than a STA identifier included in the first HE-SIG-Bportion.
 4. The method of claim 1, wherein the HE-SIG-A field indicatesa length of the first HE-SIG-B portion and the second HE-SIG-B portion.5. The method of claim 1, wherein the first HE-SIG-B portion and thesecond HE-SIG-B portion are aligned in time.
 6. The method of claim 1,wherein the first channel is a 20 megahertz (MHz) channel and the secondchannel is a 20 MHz channel.
 7. A method performed by a station (STA),the method comprising: receiving, in a high efficiency (HE) signal A(HE-SIG-A) field of a multi user (MU) HE physical layer convergenceprocedure (PLCP) protocol data unit (PPDU) (MU-HE-PPDU), an indicationof a modulation and coding scheme (MCS) of a high efficiency signal B(HE-SIG-B) field of the MU-HE-PPDU; receiving the HE-SIG-B field inaccordance with the indicated MCS, wherein the HE-SIG-B field comprisesa plurality of STA identifiers; and receiving data of the MU-HE-PPDU,wherein at least one of the STA identifiers of the HE-SIG-B fieldcorresponds to an identifier of the STA; wherein the HE-SIG-B fieldcomprises a first high efficiency signal B (HE-SIG-B) portion and asecond HE-SIG-B portion which is different than the first HE-SIG-Bportion.
 8. The method of claim 7, wherein at least one of the firstHE-SIG-B portion and the second HE-SIG-B portion comprises a commonportion and a variable length user specific portion.
 9. The method ofclaim 7, wherein the first HE-SIG-B portion comprises at least some ofthe plurality of STA identifiers and the second HE-SIG-B portioncomprises other STA identifiers of the plurality of STA identifiers. 10.The method of claim 7, wherein the first HE-SIG-B portion and the secondHE-SIG-B portion are aligned in time.
 11. The method of claim 7, whereinthe first HE-SIG-B portion is received on a first 20 megahertz (MHz)channel and the second HE-SIG-B portion is received on a second 20 MHzchannel which is different than the first 20 MHz channel.
 12. The methodof claim 11, wherein the HE-SIG-A field occupies an 80 MHz bandwidth.13. The method of claim 12, wherein the HE-SIG-B field is comprised of athird HE-SIG-B portion and a fourth HE-SIG-B portion which is differentthan the third HE-SIG-B portion; wherein the third HE-SIG-B portion isreceived on a third 20 MHz channel and the fourth HE-SIG-B portion isreceived on a fourth 20 MHz channel which is different than the third 20MHz channel.
 14. A station (STA) comprising: a receiver configured toreceive a multi user (MU) high efficiency (HE) physical layerconvergence procedure (PLCP) protocol data unit (PPDU) (MU-HE-PPDU),sent from an access point (AP) to a plurality of STAs, wherein theMU-HE-PPDU comprises a high efficiency signal A (HE-SIG-A) field thatindicates a modulation and coding scheme (MCS) of a first highefficiency signal B (HE-SIG-B) portion and a second HE-SIG-B portion ofthe MU-HE-PPDU; wherein the first HE-SIG-B portion and the secondHE-SIG-B portion are received on different channels; wherein the firstHE-SIG-B portion and the second HE-SIG-B portion comprise differentinformation.
 15. The STA of claim 14, wherein the first HE-SIG-B portioncomprises a plurality of STA identifiers.
 16. The STA of claim 14,wherein the second HE-SIG-B portion comprises a STA identifier which isdifferent than every STA identifier included in the first HE-SIG-Bportion.
 17. The STA of claim 14, wherein the HE-SIG-A field indicates alength of the first HE-SIG-B portion and the second HE-SIG-B portion.18. The STA of claim 14, wherein the first HE-SIG-B portion and thesecond HE-SIG-B portion are aligned in time.
 19. The STA of claim 14,wherein the first channel is a 20 megahertz (MHz) channel and the secondchannel is a 20 MHz channel.
 20. The STA of claim 14, wherein theHE-SIG-A field spans a 40 MHz bandwidth.